In known coating techniques, an antireflective coating and a wavelength tunable film for interrupting specific wavelength light are applied over a wide area for solar cells, display panels, and lighting apparatuses.
For example, a die coating method is disclosed in Japanese Patent Laid-Open No. 2003-260398. FIG. 13 is a schematic diagram for explaining the conventional die coating method. When a functional film is applied to a substrate 113, a coating solution 112 is applied onto the substrate 113 from a die 111 extended in a coating width direction, through a slit formed along the length of the die 111.
In some cases, a coating solution is applied to a substrate through a porous material soaked with the coating solution. For example, coating apparatuses and coating methods described in Japanese Patent Laid-Open No. 63-229166 and Japanese Patent Laid-Open No. 63-39357 are known.
FIG. 14 illustrates the structure of the coating apparatus disclosed in Japanese Patent Laid-Open No. 63-229166. The coating apparatus causes a coating solution 115 supplied from a dispenser to penetrate into a porous material 116 and then presses the porous material 116 onto a chip 117, deforming the porous material 116 so as to press the coating solution 115 out of the porous material 116. Thus, the coating solution 115 is applied onto the chip 117.
FIG. 15 is an explanatory drawing illustrating a printing method of a printer disclosed in Japanese Patent Laid-Open No. 63-39357. The coating apparatus includes a porous material having a two-layer structure composed of an upper porous material 118 and a lower porous material 119. The bubble diameter of the upper porous material 118 is larger than that of the lower porous material 119. The upper porous material 118 is soaked with a coating solution beforehand, and then the solution is transferred from the upper porous material 118 to the lower porous material 119. The lower porous material 119 is then pressed to the substrate 113 to print the coating solution 112.